Feeding system



March 22-, 1932. I p 5' CARTER 1,850,980

FEEDING SYSTEM Filed May 14. 1930 I INVENTOR ATTORNEY PHIUP 51m ARTER BY wv-f/t Patented Mar. 22, 1932 rone'rlou or AMERroA,,A CORPORATION or DnrJAwAnni iinniims srsrn vr Application filed ma 14, 1930. Serial means.

Thisjinvention relates to a feeding system and has as one ofits objects the provision-of a new and useful method and means for supplying energy to an antenna system having f8? a plurality of radiating elements one-of which maybe considered an antenna, andthe other of which maybe considered an energized refiector therefor. I In order to obtain efficientunidirectional 10 radiation, energizediradiating elements are used spaced apart an odd number of quarter wave lengths. For maximum efiioiency, it'is necessary that the power radiated is equal in each of the elements and at a predetermined 5 correct phaserelationship. In order to energize the antenna and reflector forming part of the system outlined, supply lines connected to each radiating element, tied together at some point and connectedto a transmission 20 line leading-t0 a sourceofvhigh frequency,

energy, are supplied with energy-from the sourcel In order to obtaincorrect power distribution heretofore, one of the radiating elements was matched-to: its supply l ne and matched to the other supply line. After both were matched it was found,- upontesting the first supply system, that it was unmatched,

because of various interactions caused during '30 the matching of the second system'and the reaction between the .reflector'and antenna; As a consequence of this,'tun1ngof the an electro-magn'etic wave propagation. Briefly, this ob ect is accomplished byunty ng orleavin free the su )1 linesat their junction pointpand alternately matching and tuning the radiating elements oft he respectiye sup- E0 ply lines." iThen, whenth1s is finally accom subsequently the other radiating'element was plished, the supply lines maybe connected to:

gether atanypoint and there will 'becorrect power distrlbution and phase relationship of the energy in the radiating elements; namely,

the antenna: and reflectonto give the desired V propagation,

Theinve'ntion as outlined briefly inthe foregoing statements may be more fully understood by the remarks which are to follow directed particularly towards the accompanymg drawings, in which;

Figure 1 illustrates a transmission line ter- Y minated by a non-reactive'impedance,

I Figure Qillustrates a' line similar tothat given in Figurel but an odd' number of quarter wavelengths shorter than the line of Figure -1,'

Figures 3 and 4 indicate standing "waves of c isrz 'rss P T EN.-r QFFI rtrrmrsraars'canrnn, or roar J'EFFERSOR'NEW YORK, assrenon'ro are-1'0 con-f 4:)

current and potential-in thelines shown in- Figures 1 and'2 under-certain conditions, and

'70 features of the present 'inven 'Figure 5 discloses aradiatingsys'tem incor porating the tlon. r

i If the two lines a ,'r,-shown in Figuresl' and i 2, have a surge impedanceequal to Z and diner in length by any odd number ofiquarter Wave lengths, an'd'line a is loaded Witharelsistance equal to 74 X Z and line r loaded with a resistance r then, standingwaves will" be set up on the lines afl". Assuming 70 to beless than unity, f the load A on line a approaches a short cir-, cuit as a result of which therefis apotential minimum and a current maxinum at point A as shown in Figure-3. M a As the load R on line r approaches infinite impedance, or an open circuit, therewill be, as shown in"Figure 4, a maximum potential and a minimum current value "at point B.

Fronr the curves of "Figures3 and 4it should be apparent, therefore, that the impedance along adjacent points of linesa, 1" is the same and that they may be coupled, connected or *tied'together infany suitable fashion. V.

The foregoing conditions exist in'the'case of the antennasystem shown in;Figu'reftii .where loads A and R areindependently non r reactive, but mutually reactive. Supply lines a, 1* feed through impedance matching devices 2, 4, antenna A and reflector R respectively. Because of the spacing of the antenna A and reflector R line a is an odd number of quarter wave lengths longer than line 0*. This is indicated by the factor n on the drawings which indicates any odd numher. The supply lines a, r are fed from a transmission line 7 T from a source S of high frequency current through impedance matching device 6 which connects transmis sion T to the tying point 8 of lines a and 7".

Now, in the system described in Figure 5, by virtue of the mutual-action between the antenna and reflector when energized, the impedance of the antenna is caused to decrease and, the impedance of the reflector is caused to increase. Since action and reaction are always equal and opposite, if the antenna impedance is decreased by a certain ratio 70, reaction on the reflector will cause an increase in its impedance according to the ratio Consequently, as the conditions outlined above in connection with Figures. 1 to 4 for the tying together of lines" a, a", are satisfied, lines a and 7", of Figure 5, maybe tied together at any point 8. Tying, accord ing to this invention is done after antenna A has been tuned in which condition it presents a resistive load, and matched to line a with reflector 7" short circuited, detuned or otherwise unenergized and disconnected. Similarly and subsequently antenna A is dis-' connected and deenergized, and reflector R is tuned-and matched toits line 1". Still later, at tying point 8, the antenna system may be matched by means ofimpedance matching device 6 to transmission line T to which it is connected.

Tying together of lines a and 1": at any point 8 after the tuning and matching procedure outlined has been carried out may be done by virtue of the tact that itcan be demonstrated that if two similar transmission lines differing in length by an odd number of quarter wave lengths are loaded with resistances, one having the ratio K to the surge impedance and the other having the inverse ratio V V to the surge impedance, the impedance oflered at the input ends are identical regardless of the actual total length.

This is, in order to properly couple the system shown in Figure 5, the reflector It, after being thrown out of tune is left disconnected from its supply line 7 and unenergized while the antenna. impedance is matchedby impedance matching device 2to the surge impedance of line a and the antenna tuned. The antenna is then disconnected from its line, short circuited or detuned, and the reflector is tuned, connected to its line 7" and matched thereto through its impedance matching device 4. Now, if the supply lines a and 1" after removal of short circuits and .disconnections are tied together at any point such as 8, the high frequency power from source S will divide equally and in correct phase between the antenna and reflector despite the fact that by virtue of their mutual action their impedances are no longer equal; for, although the current in the reflector causes a decrease in the antenna impedance, the current in the antenna causes an increase in the reflector impedance and reflection takes place on both lines, due to the fact that the antenna and reflector are separated by an odd number of quarter wave lengths, the impedances at the point where lines a and 1 are connected together are equal and consequently power from source S divides equally between the two lines.

Proper current division and correct phase relation can theoretically be obtained by first connecting lines together at'point 8 but it is a' long and difficult process, when A is matched to its line, adjustment of matching circuit for R throws out the matching of A. Then, when A is readjusted R goes out etc. This, all due to action and reaction of radiation from A on R and from R on A. After several see-saw adjustments correct result can be approximately obtained.

I claim: i

1. In a system comprising a pair of elements, independently non-reactive when supplied with energy of a certain frequency but mutually reactive at that frequency; a source of energy; and, separate lines from thesource to each of the elements; the method of coupling the system together which includes alternately deenergizing one element while matching the other to its supply line and then tying the lines together.

2. In a radiating system comprising a pair of radiating elements,-a source of energy, and separate lines from the source to each of the radiating elements, the method of coupling the apparatus together which includes deenergizing one radiating element while matching at a predetermined frequency the other element to its supply line, deenergizing the matched element while tuning and matching at the same aforementioned frequency the formerly deenergized element to its supply line and subsequently coupling the two supply. lines together.

3. In a radiating system comprising an antenna, a reflector, a source of energy, and lines from the source to the antenna and re flector for energizing the same, the method of coupling the antenna and reflector to the source which includes 'deenergizing the reflector matching at a predetermined frequency the impedance of vthe antenna to its supply line, deenergizing the antenna, matching at the same aforementioned frequency the impedance of the reflector to its supply line With the antenna deenergized, and coupling, the supply lines together.

4:. In a radiating system comprising a pair of tuned radiating elements, a source of 10 energy for exciting the elements and supply a lines for supplying energy from the source to the elements, the method of connecting the source, lines; and the elements together which includes alternately deenergizing the elements While matching at the same frequency the remaining tuned element to its respective supply line, tying the supply lines together after matching at the same frequency each element to its supply line and connecting the 2 source to the supply lines at the tying point.-

PHILIP STAATS CARTER. 

